XML 20 R28.htm IDEA: XBRL DOCUMENT v3.3.0.814
Compensation Plans - Roll-Forward of Outstanding Restricted Stock Grants Issued (Detail)
9 Months Ended
Sep. 30, 2015
$ / shares
shares
Shares  
Outstanding shares, Beginning Balance (shares) 306,768
Outstanding shares, Ending Balance (shares) 310,456
Restricted Stock Units (RSUs)  
Shares  
Outstanding shares, Beginning Balance (shares) 335,768
Grants issued (shares) 74,650
Grants vested (shares) (77,462)
Grants forfeited (shares) (3,500)
Outstanding shares, Ending Balance (shares) 329,456
Weighted-Average Grant Date Price per Share  
Weighted-Average Grant Date Price per Share, Beginning of Period (usd per share) | $ / shares $ 79.79
Weighted-Average Grant Date Price per Share, Grants issued (usd per share) | $ / shares 167.56
Weighted-Average Grant Date Price per Share, Grants vested (usd per share) | $ / shares 73.16
Weighted-Average Grant Date Price per Share, Grants forfeited (usd per share) | $ / shares 77.81
Weighted-Average Grant Date Price per Share, End of Period (usd per share) | $ / shares $ 105.92